There's a good amount of subjectivity regarding baseball prospects. With the evaluation of talent being in the eye of the beholder, finding consensus is often difficult. Even Jim Callis and Jonathan Mayo at MLBPipeline.com don't always see eye to eye on everything. They'll be discussing their viewpoints regularly in a feature called "Pipeline Perspectives." Submit a topic for them to debate..

Which recently called up hitting prospect will have the biggest impact on the pennant races?

I'll concede that Reds outfielder Billy Hamilton is the most exciting position player recently added to a big league roster. He's the quickest player in baseball, and he might one day break Rickey Henderson's Major League record for steals, just like he shattered Vince Coleman's Minor League mark.

Jonathan Mayo makes a case for Hamilton having more impact on the pennant races than any late-season position-player callup. While his dynamic speed has allowed him to wreak havoc as a pinch-runner, stealing four times in four appearances, Hamilton has yet to notch his first big league plate appearance or even appear in the field. He also struggled against Triple-A pitching this year, and at the plate he might not be more than another Coleman -- a hitter with a so-so batting average and batting eye and little power.

There's only one recent callup who's getting semi-regular at-bats and producing, and he also happens to be one of the game's elite prospects. Shortstop/third baseman Xander Bogaerts could be for the Red Sox what Manny Machado has been for the Orioles.

Since signing him for $410,000 out of Aruba in 2009, Boston has tried to give Bogaerts ample development time at each level. Instead, he has been so good so soon that he hasn't allowed that to happen.

The Red Sox planned on letting Bogaerts make his North American debut in the Rookie-level Gulf Coast League in 2011, but he dominated extended spring camp so much that he pushed his way to low-Class A Greenville, where he hit 16 homers in 72 games as an 18-year-old. By the end of 2012, he was in Double-A, and he advanced to Triple-A this past June and arrived at Fenway Park in mid-August. Along the way, Bogaerts batted .296/.373/.489 with 54 long balls in 378 Minor League games.

The third-youngest player in the Majors, behind only Jurickson Profar and Bryce Harper, the 20-year-old Bogaerts has been anything but overmatched against far older competition. He has eight hits in 24 at-bats, including a homer Saturday against the Yankees' Jim Miller, and has struck out just three times. Bogaerts also has turned in some highlight plays while playing errorless ball in five games each at shortstop and third base.

Boston could turn Bogaerts loose more than it has, but for now, the club is content to platoon him at shortstop with Stephen Drew and use him as a backup to Will Middlebrooks at third base. Should Drew get injured or Middlebrooks slump -- both of which happened in the season's first half -- Bogaerts will find himself playing regularly in October.

With Drew headed for free agency, Bogaerts could be the Red Sox's Opening Day shortstop next April at age 21. He generates plenty of bat speed from the right side of the plate without overswinging, so he projects to be a high-average hitter who hits about 30 homers per season. The biggest question mark about Bogaerts coming into 2013 was his plate discipline, but he helped answer that by drawing 63 walks in 116 Minor League games.

Though he's already 6-foot-3 and 185 pounds and figures to eventually outgrow shortstop, Bogaerts may remain there longer than originally expected. He has sure hands and solid range, as well as plus arm strength and the ability to make throws from different angles.

Regardless of where he plays, Bogaerts should be a star. And he should outperform all the other position players called up late this season.

Jim Callis is a reporter for MLB.com and writes a blog, Callis' Corner. Follow @jimcallisMLB on Twitter. This story was not subject to the approval of Major League Baseball or its clubs.